package com.example.tools;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.Map;

public class HttpRequestUtil {
    /**
     * 向指定 URL 发送POST方法的请求
     *
     * @param url 发送请求的 URL
     * @param param 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param, Map header) {
        PrintWriter out = null;
        BufferedReader in = null;
        URLConnection conn = null;
        StringBuilder jsonStr = new StringBuilder();
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            conn = realUrl.openConnection();
//            conn.setConnectTimeout(20000000);
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            if (header != null)
            {
                conn.setRequestProperty("EngineCode",header.get("EngineCode").toString());
                conn.setRequestProperty("EngineSecret",header.get("EngineSecret").toString());
            }
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数
            out.print(param);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            InputStreamReader reader = new InputStreamReader(conn.getInputStream(), "UTF-8");
            char[] buff = new char[1024];
            int length = 0;
            while ((length = reader.read(buff)) != -1) {
                String result = new String(buff, 0, length);
                jsonStr.append(result);
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！"+e);
            e.printStackTrace();
        }
        //使用finally块来关闭输出流、输入流
        finally{
            try{
                if(out!=null){
                    out.close();
                }
                if(in!=null){
                    in.close();
                }
            }
            catch(IOException ex){
                ex.printStackTrace();
            }
        }
        return jsonStr.toString();
    }
}
